Electric-motor-controlling apparatus.



H. W. LEONARD. ELECTRIC mowon CONTROLLING APPARATUS. I APPLIOATION IILED MAY 11, 1909.

981,579. Patented Jan. 10, 1911.

2 BHBETS-SEEET 1.

gvwawfoz H. W. LEONARD.- I ELECTRIC MOTOR CONTROLLING APPARATUS.

AIPPLIOATION FILED KAY 11, 1909. 931,579, Patented Jan 10,4911.

2 BHEETS.SHEET 2.

avwemfoz $51 1144 mmfi UNITED STATES PATENT OFFICE.

HARRY WARD LEONARD, OF BRONXVILLE, NEW YORK.

ELECTBIG-MOTOR-CONTBOLLING APPARATUS.

Specification of Letters Patent.

Patented Jan. 10, 1911.

Original application filed January 23, 1905, Serial No. 242,203. Renewed February 20, 1907, Serial N0.

To all whom it may concern fication different other views.

Be it known that I, HARRY When LEONARD, a citizen of the United States, residing at Bronxville, in the county of Testchester and State of New York, have invented certain new and useful Improvements in Electric-Motor-Controlling Apparatus, of which the following is a full, clear, and exact specification.

This invention relates to electric motors, and particularly to the provision of means which will insure the proper operation of controlling devices therefor.

This application is a division of my pending application filed January 23, 1905, Se rial No. 242,203, renewed February 20, 1907, Serial No. 358,417.

By my invention I provide controlling means for each element of the motor and the controlling means of one element are functionally related to those of the other so that they are necessarily operated in a proper manner. I therefore protect the motor and other portions of its circuit from the objectionable or injurious effects due to improperly starting up or operating a motor when the strength of its field is less than a desirable amount. I also provide suitable protective devices which will respond to protect the motor under abnormal conditions, all of which cooperate to secure freedom to the motor from any harmful effects. I My invention may be embodied in various arrangements and forms of construction, some of which are shown in the accompanying drawings,'and the form illustrated in each figure comprises my invention and represents one specific embodiment thereof.

Figures 1 to G of the drawings are diagrammatic views illustratingpreferred forms of my invention, each showing a modifrom that shown in the Similar parts are indicated by the same reference character in each of the figures.

Referring. to Fig. 1, the supply terminals of a constant electromotive force circuit are indicated at l, 2, the motor armature at 3, and the motor field at 4. A star-ting resistance 5 is shown connected in the armature circuit and a resistance for varying the field strength is indicated at 28. The mains from the supply terminals 1, 2 pass to the double pole circuit breaker one line in- Divided and this application filed May 11, 1909. Serial No. 495,358.

cluding the overload coil 33. The core of the latter trips the latches indicated at 34 upon its upward movement, due to overload, whereupon the spring pressed switches are forced outward and open the main circuit. The arm 35 of the starting rheostat is spring pressed, tending to return it to the.

starting position. This arm does not open the circuit at the rheostat, but at its initial position strikes the rod 36 which will open the circuit breaker-32 by raising the core' of coil 33 by means of the lever 37 and rod 38. The rod 36 is normally forced into the path of arm 35 either by a spring as 39 or through gravity. The arm 35 is held inits final position by a latch 40. This may be tripped by the fall of a core 41 which is held up during operation by its coil which is shown in series with the field 4. This coil therefore acts as a no-voltage release.

In order to prevent improper starting, I provide a locking device for the arm 35. This is shown as a solenoid 42, the plunger of which carries a catch 43 having one of its faces inclined. The coil of the solenoid may have a resistance in series with it and is connected between the arm 29 of the field rheostat 28 and the initial contact of the rheostat. The excitation of coil 42 will consequently depend upon the drop in volts upon the field resistance which is dependent upon the position of arm 29. When the drop in volts is a predetermined amount, the core of solenoid 42 is raised and the catch 43 projects into the path of an extension 44 on arm 35 permitting the extension to ride over the inclined face in one direction, but afterward locking the arm from movement in the opposite direction.

Upon opening the main circuit or'upon the occurrence of no-voltagc, the arm will be released by the action of core 41 and its spring will force the arm to its initial position and the blow on rod 36 will open the circuit breaker 32 as above explained. There is sufficient lost motion of the parts so that the core of coil 33 is not raised by rod 38 when the arm 35 is at rest in its initial position on the first contact. If, up on again starting, an excessive resistance is in the out the field resistance when the' catch 43 will fall. Thisfigure shows running conditions and with all the fieldresistance cut in.

In Fig. 2 the'starting rheostat is in this instance provided with two arms 7 8, pressed .toward each other by a spring 9. The arm position and .in this position closes the switch or arm 8, as for example, by engagement'fofan abutment 14. A no-voltage or low voltage magnet 15 is provided for holdthe arm 7 when all starting resistance is cut out. Whenthe current supply is interrupted, one very low voltage occurs, the magnet 151s deenergized, or its sti'e h reduced, thearm 7 returning to the o i- -tion by pressure of 9. .The fiel resistance' 28 is control the freely movable arm'x29. The plunger 12 of the overload device is provided in this case'with an additional core 49 on which two coils, 50 and 51, tend to act. Coil 50 is connected around the resistance 5, or if desired may include only a portion thereof. Coil 51 is connected from the initial contact of the field resistance to the arm 29. Coil 50 will therefore be subjected to the. drop in volts which occurs upon the starting resistance and coil 51 to that which occurs upon the field resistance. When current passes in only one of these coils, it is insufficient to raise the plunger, but when the current passing in one is aided by a current passing in the other, the plu r will be raised and trip the latch 11, wh1ch will cause the main circuit to be opened. If upon closing the main circuit in starting by means of arm 7 any appreciable amount of field resistance is cut in, the current in the two coils 50 and 51 co-act to'raise the plunger and the arm 8 will be thrown to open the circuit. Before startingagain,

will move arm 29 to .cut outthe operator the field resistance and the motorwill then be started under full field strength. I After the starting resistance is cut out and the motor is u to speed, the arm 29 may be manipulate to vary thefield resistance as desired. Increasing the field resistance will not then trip the latch 11, although 9. current will flow in coil 51, since there will then be no current in coil 50.

In Fig. 3 I also illustrate a starting rheostat and overload device.- In this case I show an auxil ary switch in the main circuit comprising twipivotediarms 52, 53 pressed toward each 0t "er by a spring 54. T e arm 53 is manually operated and enQgeS a con-' tact which holds it in position y friction.

.the arm 52 tobe ope opened unless the fie The arm 52 is forced to engage its contact by movement of arm 53 against an abutment on arm 52- A latch 55 will hold the arm 52 in engagement with. its contact and is adapted to be tripped by the upward movement of the plunger 56. When current flows in either co 57 or 58 the plunger will notbe raised, but when the current fiows in both of the coils they act accumulatively and raise the plunger to tri latch 55, permitting nected across the armature resistance 5 and the coil 58 is connected so as to be subjected to the volts dropped on the field resistance. Hence, upon starting, this switch will be d resistance is cut out and it will be necessary to move the arm 29 to the initial contact before the motor can be speeded u In Fig. 4 l have shown the starting rheostat as provided with a spring pressed arm 59 adapted to be heldin its final position by the no-voltage magnet 15. In the main circuit is inserted the switch having the two pivoted arms 52, 53 pressed toward each other by the spring 54 and having the latch 55 as explained with reference to Fig. 3.

The plunger 56 is provided with a coil 58 connected as in Fig. 3 'to the field rheostat and the coil 60 is connected in the main circuit between the resistance 5 and the contact 61. The coil 60 will therefore act as an overload coil and trip the latch 55 upon the occurrence of an abnormal current. When starting, the arm 52 is madeto engage contact 61 b' means of arm 53 andthen arm 53 is mov to engage its contact. The main circuit is closed by moving the arm 59 to the initial contact and if an undersirable 'amount of resistance is in the field circuit,

thecurrent which will flow in coil 58 will act with the current in coil 60 to raise the plunger and o nthe main circuit. Before again attempting-to start, the field resistance must be cut. With this arrangement it is impossible to take under running conditions, as 'largea current when the field is weak asinaybe" taken when the field isstrong' This iii desirable on account'of the objectionable sparking which is likely to picpgr when a large loadis carried on a weak In Fig. 5' I show a double pole circuit breaker and the spring pressed arm 59 of the starting rheost-at has no open position.

. The coil 57 is con The lunger of the circuit breaker is provid with two cores 62, 63, preferably rigidly connected. The core 62 is provided wlth two coils 64, 65, the coil 64 being connected in the main circuit and the coil 65 to the initial contact of the field rheostat and to the arm 29. The coils act accumulatively to raise the core 62. The.coil 66 acts to raise the core 63 and is connected across the line through a resistance (Strand a switch (38. The blade of the latter is carricd by a pivoted lever (39 which is engaged by an extension 70 on the arm 53). \Yhcn the arm Si) is moved from its initial position it opens the switch (58 against the pressure of a spring 71. \Vhen the switch (38 is closed, the current passing in coil 66 will be suiiicient to raise the plunger and open the circuit breaker. This coil will therefore protect the armature resistance and other parts ofthe circuit against damage which might result from leaving arm 59 in the initial position for an unusual time. This condition might arise upon failure of cur rent for a brief interval, causing the arm to return to itsinitial position and then subjecting theresistance to-the current when restored. The same condition might arise if the circuit of magnet 15 alone were accidentally interrupted. The opening of the circuit breaker by coil 66 therefore avoids such a condition. When an abnormal-current passes in coil 64 the clrcuit breaker w ll be opened in the'usual manner. If in start ing, there is resistancein the field, the current in coil will cooperate with that in 64 and open the circuit breaker and necessitate cutting out the field resistance. In this ar .rangement, as in Fig. 4, a less overload cur rent is permissible when the field'is weak than when the field is strong. In starting, the field rheostat should be moved to shortcircuit position and the arm 59 should then be moved slightly until the switch 68 is opened, then while holding the arm 59, the

two arms of the double pole circuit breaker should be closed successively.

In Fig. 6, I provide the starting rheostat having the two 5 ring pressed arms 7, 8, with the latch 11 or the arm 8 and the no voltage magnet 15 for arm 7. An overload double pole circuit breaker 32 is connected in the main circuit. In this case the plunger 12 for tripping the latch 11 is provided with two coils T2, 73 which act accumulatively.

The coil T2 is connected in series with the starting resistance 5 between the last two contacts in place of a resistance step. The coil 73 is connected in series with the field resistance 28 and between the first two contacts in place of a resistancestcp. The starting current passing through coil '72 is not sufficientto raise the plunger 12 but when assisted by the field current will be raised and the arm 8 released. In starting, the arm 7 is moved to oil position shown in the drawing, closing arm 8 and the two sides of the circuit breaker 32 are then closed successively. The arm 7 is then moved to .the first contact of the starting resistance. If any resistance is in the field circuit, the latch 11 will be tripped, since the plunger 12 is acted upon by both the field and the armature current in coils 72. 73. The arm .29 must therefore be returned to the nitial' contact of the field rheostat before the motor can be started. \Vhen the starting arm 7 is moved to the final contact after properly starting, the coil 72 will be cut out of circuit and the field rheostat may be varied as desired, the'current in coil 73 alone not being sniiicient to raise the plunger. The-circuit breaker 32 may be set to higher amperes than the coil 72, permitting large motors to be started on friction or light loads by means of a small starter and the motor may afterward be heavily loaded andvaried in speed by means of the field rheostat. This ar angement will be desirable for very large motors which receive heavy overloads after being started.

hiany other modifications of my invention may be developed and various changes in the connections may be made and accomplish substantially thesame results.

It will be understood that instead of using a starting rheostat contact switch, I may, in some cases, omit the starting resistance and use a plain switch. I may sometimes use a controlling armature resistance for varying the speed, in which case the arm of the rheostat would be freely movable and remain in any position placed.

It is not necessary in those cases where I provide a coil which is subjected to the drop in volts on the field rheostat, as in Figs. 1,

2, 3, i and 5, to connect .one end of the coil to the controlling arm of the rheostat as shown, as the same result will be obtained by connecting to the final contact of the rheostat or to some intermediate contact. Also, although I have indicated resistances in the circuits .ofsome of the coils which act automatically to causea circuit to be opened, it will be understood that in some cases they may not be necessary and may be made adjustable if desired to change the volts dropped in them.

As my invention is susceptible of a variety of embodiments, all within the scope and spirit thereof, I do not wish or intend to limit the same to the specific construct-ions herein described, or otherwise than as expressed 1n the following claims.

iHavmg thus described my invention, I

declare that what I claim as new and desire to secure by Letters Patent, is

1. The combination of an electric motor, a resistance for controlling the armature circuit of the motor, a resistance for controlling'the field strength of the motor, and means for insuring starting of the motor onlywith a field of proper strength, said means comprising an electro responsive winding connected across said field resistance.

2. The combination of a shunt wound motor, a starting armature resistance, a variable field resistance, and electroresponsive means comprising a winding in series with condition of weakened field, said means come the shunt field winding and in parallel with said field resistance for preventing the starting up of the motor when the field is in a weakened condition.

3. A dynamo electric machine having a field jwinding, a field controlling resistance.

in series therewith, a magnetic winding con:v nected across the terminals, of said resistance, and means controlled by said latte]:v winding and controlling said field winding.

4. The combination of an electric motor, a field rheostat for varying the speed of the motor upon, a constant electromotive 'foree circuit, and electrically controlled means for preventing startingup of the motor under a prising a controlling windin subjected to the voltage across said field r eostat.

5. The combination with a motor, of a resistance for weakening the field strength of the motor for the purpose of increasing its speed, and electrical means for preventin the starting up of the motor when the field is in a weakened condition, said means comprising a'magnetic winding subjected-to the voltage across said resistance, and'a 'magnetic element movable 1n response to an increase of the magnetic strength of said winding.

(3. The combination with a motor havin a shunt field winding, of a rheostat for said field winding, a starting rheostat, means tending to move the contact arm thereof toward the initial position, means for holding said arm and which is responsive to release said arm when the supply voltage falls below a certain amount, and means electrically controlled for preventing the startin of the motor when the field is in a weaken condition, said latter means comprisir a eld trolling the motor armature circuit, means for varying the field strength, a no-volta e protective device, an overload protective e- .vice, and electrical means for preventing the starting up of the motor when the field is m I a weakened condition, said means comprismg a magnetic winding, controlling the movernent of said switch.

9. The combination of an electric motor,.

two independently closable switches in series with each other and with the armature of the motor, means for causing the automatic opening of said switches upon overload, a resistance device having a spring actuated resistance controlhng movable element in movable element, a fie d controll' for insurin the starting of the series in said circuit, a no-voltage device for controlling said movable element, means dendent upon the movementof said element or causing the opening of at least one of said two switches to (protect the circuit, means for varying the fiel strength of the motor, and means dependent upon said field va ingmeans for insuring that the field of e be of proper strength when the said-resistance is cut out to start the motor. --10. {The combination of an electric motor,

: "ce controlling the armature circuit 'andlhaving a movable element automaticall movable in response to no-voltage, a swi in series therewith, means for causing the automatic opening of said switch in response to overload and in response to movement of said movable element, a field varying resistance of the motor, and electrical means correlating said field resistance and said armature controllin resistance.

I 11.-The com ination of an electric motor, an armature controllin resistance having a resistanoe, and electro-responsive means or preventing the movement of said element to cut out the armature resistance except when the field has proper strength.

12. The combination with an electric motor, of an armature rheostat, means for varying the field strength, a 110-voltage protective.

device, an overload'protective device, and electrical means for preventing the removal of the armature resistance from circuit when the field is in a weakened condition.

13. The combination with an electric motor, of a resistance in the armature circuit thereof, means for removing said resistance from said circuit, a resistance for the field circuit of the motor, and a circuit in shunt to said field resistance and containing.an elect'ro-res nsive winding, said electroresponsive winding acting to insure the starting of the motor onl under predetermined conditions of the field stren h. g 14. The combination wit a motor field rheostat adapted to weaken the field 'of the motor, of an electroresponsive means in parallel with the resistance of said rheostat which is in circuit, and'means controlled by said windin for protectively controlling the condition 0 the motor field when the motor is started.

15. The combination with a motor field winding, of a resistance in series therewith, an electro-r'esponsive device in parallel with said resistance whereby the current of midelectroresponsive device is dependent upon the amount of said resistance which is in series with said field winding and means controlled by said electro-res xk otor with a proper fiel strength.

16. The combination with an electric motor, of a field resistance in with the sive device field winding, and motor protective means comprising a magnetic wlnding in series with the field winding and in shunt With said field resistance.

17. The combination of a shunt Wound motor, an armature resistance having a movable controlling element, a locking device for said element adapted to prevent the movement of the same under certain conditions, and electrical means for controlling said locking device, said means being dependent upon the condition of the shunt field circuit of the motor.

18.,Tl1e combination of a shunt Wound motor, a magnetic Winding functionally related to the shunt field Winding of the motor, an automatically movable element controlled by said magnetic Winding and movable in response to a condition of the shunt field circuit, and means controlled by said movable element for protecting the motor against abnormal operation.

}In testimon whereof I affix my signature, in presence 0 two Witnesses.

H. VVARD LEONARD.

Witnesses:

C. J. CORNELL, Gn. J. SoHELz, Jr. 

